Free floating mine



Feb. 12, 1957 v R. D. BENNETT 2,780,994

FREE FLOATING MINE Filed oct. 1, 194e 2 sheds-sheet 1 |e le T 'NT T T I 2 I7 f l 2 l i l l wuswvm RUBENNETT Feb. 12, R, D BENNETT FREE FLOATING MINE 2 Sheets-Sheet 2 Filed 001'.. l, 1946 FREE FLOATING MINE Ralph D. Bennett, United States Navy, Silver Spring, Md.

Application October 1, 1946, Serial No. 700,541

2 Claims. (Cl. 102'18) (Granted under Title 35, U.\S. Code (1952), sec. 266) This invention relates to a marine mine and more particularly to a mine adapted to float awash in a body of water with such an orientation therein as to maintain an inertia responsive member in a position effective to cause the energization of an electrical circuit for tiring the mine when a lateral force of predetermined intensity is applied thereto. v

Itis an objectof this inventionto provide a free floating mine including an inertia responsive device having an element which is movable under the shock of a vessel striking the mine to cause the energization of an electrical circuit for ring the mine.

It is a further object according to the preferred embodiment of athe present invention to provide a free floating mine in which an impulsegenerator'is employed to generate an electric voltage for firing the mine when the armature of the generator is set in motion by the shock of a vessel striking the mine.

A further object according to an alternate embodiment of the invention is to provide a free oating mine adapted to maintain yieldably a predetermined orientation Within the water and having a pendulum element for closing a firing circuit therefor when :the mine deviates from said predetermined orientation in response to a lateral blow received thereby.

Still other objects, features and advantages of the present invention are those implied from or inherent in the novel construction, combination and arrangement of the parts as will become more clearly apparent from the following description, reference being had to the accom panying drawings of which:

IFig. 1 is a sectional View of a free floating mine according to the preferred embodiment of the invention with `certain parts thereof appearing in elevation and with the mine positioned in the water in the desired orientation therefor, the arming switch in the ring circuit of the mine being shown in its safe or unarmed position.

Fig. 2 is an enlarged view partly in section of the impulse generator assembly of Fig. l shown with the armature thereof in a moved position;

Fig. 3 is a view partly in section and partly in elevation of a free iloating mine according to another embodiment of the invention wherein the arming switch of Fig. 1 is employed, the arming switch being shown in its armed position; and

Fig. 4 is an enlarged view partly in section of the arming switch.

Referring now to the drawings wherein like reference characters are employed throughout the several views thereof to designate the same or similar parts, and more particularly to Fig. 1,'the numeral 5 indicates generally the mine assembly including the various components thereof, one of which is the elongated cylindrical casing 6. This casing is preferably formed in two sections suitably flanged at 7 and S whereby the sections may be bolted together in the manner shown with the partition 9 adapted to be secured therebtween at the time of assembly. The partition serves to divide the casing into two compartments in one of which is arranged a quan tity of explosive 10, preferably T. N. T. cast therein after being admitted through the opening 11, now shown closed by the plate 12. By reason of this arrangement of the explosive in the casing', the lower end thereof is suihciently weighted to cause the mine to remain in a substantially upright position when floating in a body of water.

The overall weight of the mine is so adjusted with respect to the water displacement thereof as to cause the light end thereof lto remain substantially awash with the surface of a body of water when in normal oatin'g position therein, thereby to offer the smallest possible area for detection by the enemy.

-lt will be understood that in the assembly of the mine all connections may be made watertight by the use of gaskets or other suitable means, and that a plurality of annular ribs 19 may be provided in casing 6 in order to strengthen that portion of the side wall thereof which is not supported by the T. N. T.

Located within a central aperture in the separating partition 9 is a cup-like retainer 13 within which is arranged a quantity of explosive generally referred to as a booster charge 14 which is adapted to explode the main charge when detonated by the electro-responsive primer 15. The necessary current for energizing and firing the primer is supplied from the impulse generator 1'6 arranged within the cylindrical housing 17V aixed to the inner surface of the end plate 18. This generator may bc similar to that disclosed and claimed in the copending application of H. J. Plumley for Magnetic yInertia Controlled Fuze, Serial No. 535,799, filed May 16, 1944,

Such a generator must have as a part thereof, a permanent magnet member, which in this case may be either the movable armature 20 or the stationary sleeve member 21, adapted to set up a strong magnetic field within which is arranged the wire Wound coil 22.

The electroresponsive primer 15 is electrically connected to the terminals of the coil 22 by way of leads 23, in one of which is connected an arming switch 25. The primer 1S is disposed somewhat centrally within the booster charge 14 and adapted to cause the mine to be exploded when the primer is energized by receiving current from the coil 22 as a voltage is induced ltherein by a change in the magnetic flux passing therethrough, as would be caused by the upsetting of the armature or keeper 2t), as shown in Fig. 2, in response to the striking of the mine by a moving vessel, armature movement being restricted by housing 17 such that the armature is restored to the initial position Fig. 1, in the event that it is actuated therefrom prior to operation of arming switch 25.

The arming switch 25 connected within the aforementioned lead 23 of the tiring circuit is adapted to keep the circuit open until the mine has been submerged within water for a predetermined period of time. The operation of this arming switch is somewhat similarwto other such devices well known -in the art, the spring contact members 26 and 27 thereof being positioned to be brought into circuit closing engagement with the c-onducting sleeve 28 as the plunger 29 is urged inwardly of the housing 39 by the action of spring 31 upon the dissolving of the soluble washer 32 retained between the end plate 33 carried by the plunger 29 and the perforated cover plate 34. The resilient diaphragm 35 prevents water entering the air-filled portion of the mine through the housing 3i) by maintaining a seal between the housing and the movable plunger 29.

Contact members 26 and 27 are secured to an annular insulating member 36 and are normally maintained electrically disengaged by means of an insulating sleeve 37 carried by the plunger 29. Spring 3`1.is compressed bctween a nut 39 threaded on the plunger 29 and the housing 30 for actuating the plunger to the armed position when the soluble washer 32 has dissolved. The sleeve 28 and collar 37 are secured by nut 24. l

Indescribing the operation of the mine as shown in Fig. l, let it be assumed that the mine has just been released from a plane flying some distance above a body of water. By reason of the ballistic characteristics of the mine, the heavier explosive-filled end thereof will align the elongated casing with the direction the mine is falling, thereby to reduce to a minimum the shock of impact on the casing and mechanism therein by causing the mine to fall end first into the water. As previously described, the mine thereafter oats in an upright position within the water with the upper end thereof substantially awash, and by reason of the relatively large ratio of length to diameter of the mine, the mine maintains the upright position regardless of wave action whereby the probability of the armature 20 being moved to a firing position in response thereto is substantially eliminated.

Shortly after the mine has assumed this normal iioating position, the soluble washer 32 will have dissolved sufficiently as to allow the plunger 29 to move the conducting sleeve 23 into position between the contacts 26 and 27, thereby to arm the mine by closing the circuit from the detonator to the inertia generator 16. A subsequent striking of the mine by a moving Vessel after the arming thereof will upset the armature 20, as shown in Fig. 2, to thereby induce a voltage within the'coil 22 for energizing and firing the detonator vto explode the mme.

A free floating mine according to the alternate embodiment of the invention is shown in Fig. 3 and is generally designated 46. Mine 46 is generally similar to mine of the preferred embodiment except that an inertia responsive pendulous switch 40 has been substituted for the inertia generator 16 shown in Fig. 1. This arrangement requires that a battery 41 be connected in the circuit for supplying the current necessary for firing the mme.

The inertia or tiring switch 40 has as a part thereof a resilient arm or pendulum member 42 that is supported centrally of the insulating plate 43 by means of the bracket piece 44. The insulating plate is, in turn, secured by screws 45 to the inverted dish-like member 46 that is welded or otherwise secured to the closing plate 47 in the manner shown. Secured to the outer edge of the insulating disk 43 is the somewhat U-shaped bracket piece 48 upon which is mounted the stationary contact ring 49 through which is suspended the pendulum member 42. By reason of the upright orientation of the mine, the mass 50 carried at the free end of the pendulum arm causes the arm to normally assume a position centrally of the ring 49. A predetermined inertia force 4as might be caused by a vessel striking the mine, however, will cause the resilient arm 42 to be moved by the mass 50 into engagement with the ring contact member 49, thereby to complete a circuit for electrically ytiring the mine regardless of the direction of the lateral blow applied thereto, providing, however, the arming switch 25 has been properly closed on the dissolving of .the soluble washer 32, as has been previously described.

The leads 52 electrically connect the battery 41 by way of the tiring and arming switches 40 and 25 respectively, with the electroresponsive primer l5 which is threaded through an opening within the closing disk 51 of the booster charge container 13, substantially as shown in Fig. 1.

The sensitivity of the device may be varied by selecting a proper diameter of the opening within the contact plate 49, by substituting masses 50 of different weights, by substituting arms 42 of different resiliences, or by varying the position of mass 50 on the arm,`the mass being adjustably secured thereto for this purpose as by a screw 52.

While the invention has been described with reference to two examples thereof which give satisfactory results, it will be understood by those skilled in the art to which this invention appertains, after understanding Ithe invention, that various changes and modifications may be resorted to without departing from the spirit and scope of the invention as defined by the appended claims.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. In a free lioating mine of the character disclosed, the combination of an elongated cylindrical casing having an annular rib of greater diameter than the casing formed at one end thereof, a circular plate of the same diameter as the outer diameter of said rib and hermetically sealed thereto forming an air chamber, an explosive charge arranged within an `end portion of said casing in a manner to weigh the said casing so as to cause it to -oat awash in lan upright position within the water with the plate uppermost, an electroresponsive detonator adapted when energized to explode said charge, and a circuit for energizing said detonator, an inertia generator arranged in said circuit and comprising a permanent magnet for setting up a magnetic iield, a voltage generating induction coil positioned in said iield, fmstum shaped magnetic means tiltable in response to a light lateral'irnpact applied to said plate for changing said ieldsuiiciently to energize said detonator by the voltage induced in said coil, and a cylindrical support for securing the generator to the upper end-of said casing, said support encircling said magnetic means and carried interiorly by said plate in closely spaced adjacency therewith and coaxially disposed with respect to said casing.

2. In a free iioating mine of the character disclosed, the combination of an elongated cylindrical casing having an annular rib extending outwardly from one end thereof, a plate hermetically sealed to said rib forming an air chamber, an explosive charge arranged within an end portion of said casing in a manner to cause the mine to float awash in an upright position within a body of water with the rib uppermost, electroresponsive detonating means adapted when energized to explode said mine, means including a circuit for energizing said detonating means, an inertia actuated generator carried by said plate coaxial with the casing, said generator being connected in said circuit and including an induction coil, means for setting up a magnetic iield about said coil, a frustum shaped inertia responsive member in said generator and `tiltable from a position of rest in response to a light lateral impact applied to the plate for changing said ield sufiiciently to energize said detonator by the voltage induced in said coil, an arming switch including a pair of contact members connected in said circuit, and means including a soluble washer for maintaining said contact members in open circuit position until the mine has been immersed in the water for a predetermined period of time.

References Cited in the le of this patent UNITED STATES PATENTS 810,983 'Rowland Jan. 30, 1906 1,295,051 Minkler Feb. 18, 1919 1,382,374- Maxim June 2l, 1921 1,407,653 Hammond, I1'. Feb. 2l, 1922 FOREIGN PATENTS 263,985 vItaly Apr. 10, 1929 525,333 vGreat Britain Aug. 27, 1940 864,381 France Ian. 17, 1941 

